In recent times, so-called hybrid modalities are increasingly being used in medical imaging; for example, modalities designed for the simultaneous recording of computed tomography and positron emission tomography data (PET data), or modalities by which it is possible to create both magnetic resonance records and also positron emission tomography records, or magnetic resonance records and single photon emission computed tomography records (SPECT records). Other hybrid modalities are also feasible, for example a modality which is able to create both computed tomography records (CT records) and also SPECT records.
These hybrid modalities advantageously respectively provide a combination of at least one modality with a high temporal or spatial resolution (for example, magnetic resonance imaging (MRI) or CT) and at least one modality with a high sensitivity (for example, SPECT or positron emission tomography (PET) or another nuclear medicine method).
In the case of nuclear medicine images, the problem namely exists that the resolution is limited by different factors, for example by the motion of the patient during the data acquisition. On the other hand, methods such as magnetic resonance imaging have high anatomical accuracy and/or a high temporal resolution. For this reason, additional magnetic resonance imaging recording or computed tomography recording or the like is carried out in addition to the nuclear medicine recording of data in the case of hybrid modalities.
Until now it was the case that a sensible compromise was sought for the duration of the data acquisition when recording nuclear medicine data. The acquisition time should be long enough to detect a sufficient number of events, but, on the other hand, it should be short enough for the patient to be able to lie still during it. The influences of the respiratory or cardiac motions have been limited by different methods, for example by gating methods in which measured data are recorded, by way of example, only during the exhalation phase. Furthermore, there are different approaches to following the motion of the patient using optical systems so that they can subsequently be incorporated into the reconstruction of the nuclear medicine data.
However, the ability of such methods to achieve improvements in the image record is limited, or they require considerable technical complexity.